A numerical simulation of equilibrium gas flow in a binary system is presented for the case in which an accretion disc forms around the accreting star (primary). Preliminary results are shown for the mass ratios 0.4, 1.0 and 2.5. Two main conclusions are reached. First, the accretion disc is quite well defined and is comparable in size to the Roche lobe of the primary. Second, all but a few per cent of the mass transferred is accreted by the primary.